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Rollover accidents aren't frequent, but they are deadly. Even though they account for just two percent of serious crashes, rollovers are involved in over a third of all vehicle-occupant deaths. If a vehicle's roof collapses in a rollover crash, people can be killed or injured by the roof itself or ejected as a deforming roof breaks the doors and windows open. To mitigate that risk, the government has recently enacted a tougher roof-strength standard. Plus, the Insurance Institute for Highway Safety has developed a roof-strength test of its own, one that's considerably more demanding than the government's.
The IIHS tests and rates roof strength to help consumers determine which vehicles are potentially safer in a rollover. Publicizing those scores also encourages automakers to increase roof strength beyond the minimum required by law. The video below illustrates how the IIHS conducts its tests.
The Institute began testing and rating roof strength more than three years ago after determining that strong roofs reduce the risk of fatal or incapacitating injury in rollover crashes. Roof-strength is just one of a series of crash tests that determine overall vehicle crash-worthiness. Vehicles that score highest earn the Institute's Top Safety Pick award. To qualify for a Good roof strength rating, a roof must be able to withstand a force equal to four times the vehicle's weight before reaching 5 inches of crush.
Rollovers are much more common in SUVs and pickups than in cars, mostly due to their higher center of gravity. In 2011, 7,000 people died in rollover crashes, and 56 percent of SUV occupants killed were involved in rollover crashes. Electronic stability control, mandated as of the 2012 model year, has helped reduce rollovers. Seat belts and the now-common side-curtain air bags provide further protection if a rollover does happen. Of course, bags and belts are only effective if the roof maintains survival space during a crash. See the video below to learn more about this lifesaving test.
For more about vehicle rollovers, read "Rollover 101." For information on other safety technologies, visit our guide to vehicle safety.
